Gas vortex-stabilized radiation source and method,and additive-introduction means therefor



`invention;

'lines 2-2 and 3-3 of FIG-.1; I l

` cAsvoaTEx-STABILIZED aADIAnoN SOURCE AND Y Memor), A ND xDnmva-INTRQDUCTION MEANS 1 TaEkEFoR This application is a continuation-in-partof copending application Ser. No,-` 491,120, and now abandoned, filed Sep. l2 9, 1965, for Radiation: Source, and vlhiwdenSupply `Means Therefor.

This invention relates to a radiation or light source, and to a :method for generating light and similar radiation.

l An'object of the inventionv is to provide a Ahigh-eciency, .high-power radiation source and method wherein the electrifcal discharge is extremely stable. I

`Another object is, to vprovide a .high-i tensity radiation source which. is efficient in operation, and hich will run for many hours at high power levels andin the nbsence ofexcessive electrode deterioration.-

Another object is to provide a radiation source wherein particles of additive may be introduced into the arc without substantially disturbing or cooling the sarne'.v Y

Electrode 1l is provided with an axial passage 28 through which is extended a conduit 29, the conduit being (in the illustrated embodiment) substantially smaller in diameter than the kpassage so that an annulus 30 is fonned around the conduit. Passage 28 terminates at the inner end thereof -in a nozzle or constrictor means 3l, such nozzle being preferably coaxial with the electrodes. Correspondingly, conduit 29 terminates at the inner end thereof in a-nozzle or constrictor means 32. Nozzles 31 and 32 should be axiallyl spaced from each other, and nozzle 32 ispreferably smaller in diameter than nozzle 31. Nozzle 32 is also coaxial with the electrodes, being thus aimed at nozzle 31 so that particles emanating from nozzle 32 are directed toward and pass through nozzle 3l into the arc 27 (a the axial portion of chamber 17).

A suitable powder and gas source, designated schematically at 33 in FIG. l, is connected sto conduit 29. In addition, a gas outlet is connected to the passage 28. In the illustrated form,

These and other objectsfwill'become apparent from the following detaileddescription taken in lconnection with the accompanying drawings in which: l

FIG. 1 is .a schematic longitudinal centralsectional view of a radiationv source constructed in accordance with vthe present aresectional views taken,

f FIGS. 2 and 3 respectively, on

FIG; 4 is an enlarged fragmentary sectional view on line afnam.

FIG. 5 is a longitudinalisectional` view.v corresponding generally to FIG.1but illustrating a radiation or light source lwhereinvno additive-injection means are provided; 1

FIGS. 6 and 7 are 'sectionalviews taken,grespectively, on

lines' 6 6 and 7 1 of Flo. s; and

. FIG. 8 is an enlarged fragmentary sectional view on line 8-8 ofFIG.'7.4 l .n

Referring first lto-the embodiment of FIGS. 1 4, inclusive, this is'illustrated schematically to comprise first `and second elongated metal electrodes l and l1, respectively, which are suitably mounted coaxially of each other and inaxially spaced relationship. Mounted sealingly around the arcingend portions of electrodes l0'and ll, and concentrically relative to the common axis of such electrodes, are inner and outer tubu- -lar envelopes l2 and 13, respectively, formed of light-trans- Vmissive or transparent material. The mounting means for the electrodes and'for the envelopes include end elements 14 and l which are suitably adapted, as with'. sealing and other devices, to close the space around the'. arcing end portions of the electrodes and to close the ends of the annulus 16 between the envelopes. The space around the4 arcing vend portions is designated 17 and comprises the arc chamber.

The end portion of electrode is shown as. being generally conical and surrounded by a generally conicalA shroud 19 through which gas is drained from arc chamber'l7. Such lgas `flows through a plurality of radial passages- 20 (FIG. 2) and thence into a gas-outlet conduit '21 for transmission to a suitable heat exchanger 22 (adapted to cool the gas) and recircula- A tion pump 23. vFrom the outlet side of the pump, the gas flows into oneend of annulus 1,6 and thence through such annulus `and through a plurality of gas-inlet passages 24 FIGS. 3 and 4) 'may thus be maintained axially of chamber 17 and between the electrodes. Such arc, which is normally a high-current arc, is stabilized and constricted by; the vortically flowing gas in `chamber 17. Electrode 10'should be'the cathode. In certain radiation sources, the power source 26'may be a pulse source, such as a capacitor bank, so that the v.electrical discharge will Vbe a spark instead of an arc.

the gas outlet is indicated-as being a drain 34 which is caused, by a suitable cap 36, to communicate with the annulus 30.

Powder entrained in carrier gas'is discharged from source 33 and passes through conduit 29 to thenozzle 32. The gas and powder then discharge rapidly from nozzle 32. Because of the momentum thereof, the powder continues-in its rectilinear movement and passes through the nozzle 3l into arc 27, thus affecting the characteristics of thearc in various desired ways (such as altering the spectral distribution,.etc. However, the cold carrier gas emanating from conduit 29 does not pass in substantial amount through nozzle 3l but instead discharges through annulus 30 and drain 34. Thus, the arc 27 is not cooled or disturbed by the carrier gas in which the powder was entrained. 1 f

The pressure relationships should be caused to be such that the'v pressure in arc chamber 17 adjacent nozzle 3l is slightly higher (for example, oney p.s.i.) than the pressure in passage 28 adjacent such nozzle. Some arc gas thus drains through nozzle 3l and out through passage 28 and drain 34 (which should have a flow-control valve therein). Nevertheless, because of the momentum of the powder particles emanating from the nozzle 32, such particles pass into the arc 27. Thus, a,

highly desirable way is achieved in which to add particles of powder (or liquid, etc. to the arc 27 without cooling or substantially disturbing'the same.

Suitable water conduits W (FIG. l) are shown as associated with electrode l0 to effect water cooling thereof. Similarly, the electrode 11 may be continuously water cooled.

The stabilizing gas passed tangentially into the arc chamber -17 (FIG. 1) may comprise xenon, argon, krypton, etc. at relatively high pressures. The carrier gas for the particulate additive may Acomprise the same or different gases, preferably in- The particulate or powdered additive may comprise, for ex` ample, grains of sodium chloride orfrnely ground sodium means is indicated schematically at F in FIG. 5, and may be similarly incorporated in' FIG. `l.

EMBODIMENT OF FIGS. 5--8 In the embodiment of FIGS. 5--8, inclusive, the same reference, numerals have, with certain exceptions, been em- 'ployed as in the embodiment of FIGS. 1-4, such reference numerals denoting components substantially identical to those described relative to FIGS. l-4. On the other hand, corresponding but not necessarily identical parts have been given the same reference numerals except followed in each instance by the lettera.

Withy two exceptions, the structure illustrated at the left portion of the radiation or light source of FIG. 5 is identical to that of FIG. 1. The first exception is that the end of the electrode 10a illustrated in FIG. 5 is much longer, and smaller in diameter, than is the end of the electrode 10 of FIG. 1. The

second exception is that the end of electrode 10a is illustrated as protruding from shroud 19 for a substantial distance toward A electrode 11a. It is to be understood that the arcing end of 34a. It is pointed out that the diameter of the passage 28a may be-reduced to that of the opening or nozzle 31a, so that an elongated passage having a uniform diameter is created.

The gas-outlet conduit 34a from passage 28a is shown as communicating through the previously-indicated control valve (numbered 43) with the conduit 21 to filter F and heat exchanger 22. Thus, the illustrated system is fully recirculating.

The pressure of the gas in arc chamber 17 may be, for examcourse, certain lower pressures may be employed. The magenitude of the current which flows between the electrodes 10a and 11a may be, for example, on the order of 400 amperes. Such large currents may be employed despite the fact that the apparatus is relatively small. Thus, for example, the inner diameter of envelope l2 may be on the order of l :if inches. The gap between electrodes 10a and 11a may be, for example, l to l5 millimeters, although much longer gaps (such as 20 to 30 millimeters) may also be employed. v

ln the operation of the embodiment of FIGS. -8, the system is filled with xenon, or other desired gas, under a relatively high pressure such as I8 atmospheres. Pump 23 is then s et into operation to effect circulation of gas from the pump into annulus 16, thence through tangential inlet passages 24 into the region of arc chamber 17 around the anode 11a, and thence to the portion of the arc chamber located between the electrodes. The major amount of vortically flowing gas then drains from the arc chamber through the annulus defined within shroud 19, such gas flowing through passages 20 into passage or conduit 21 and thus back to the filter F, heat exchanger (cooler) 22 and pump 23.

A minor amount of gas is caused to drain through nozzle 31a and passage 28a to conduit 34a leading to the heat exchanger and pump. Thus, for example, the valve 43 in conduit 34a may be so set that approximately 90 percent of the gas within arc chamber 17 drains through passages 20-2l, and approximately percent through passages 28a and 34a. Stated in another manner, the invention contemplates causing the pressure in nozzle opening 31a and passage 28a to be only slightly lower than the pressure in the region of arc chamber 117 which is adjacent opening 31a. The pressure being only slightly lower, the gas flow through opening 31a is small.

Electrical discharge 27 is then initiated between electrodes 10a and lla. The discharge may be a steady-state arc, or a pulse or spark discharge. Relative to the latter, the discharge follows a straight line path through the canal defined within the vortically flowing gas, as distinguished from the irregular or arcuate path conventionally followed by sparks. In both pulse and steady-state operation, the discharge 27 is caused to be stable and constricted, even at high currents such as 400 amperes.

It is emphasized that, in accordance with the present method, gas is introduced into the arc chamber in a generally tangential manner and at a region radially outwardly of the lanocle lla. A major amount of such gas is then removed through shroud 19 around the cathode 10a, and a minor amount through axial outlet 31a. It has been found that this gas-flow produces an arc 27 which is surprisingly stable and `"efficient, and which produces a long electrode life. The gas which `drains through the central opening in the anode 11a is effective in producing constriction and stabilization of the electrical discharge without, however, causing the discharge to extend for a substantial distance into the outlet opening 31a. The latter is extremely important since the region of the discharge within the anode 11a is largely wasted in that the light generated thereby is shielded by the wall of the anode passage. I

Thus, it is an important featurel of both embodiments of the invention to drain only a minor amount 'of vortically flowing arc gas through a substantially axial'boire, and a major amount elsewhere. The bore is preferably in theanode With such an arrangement, the great stability of priorlart'axial-outlet light sources is approached or achieved, yet Ithe'eufficiency of the source is vastly-.improved Furthermore, electrode life is sur- Thus, such gas causes the area (footpoint region) over which the arc contacts the relatively pointed tip ofthe cathode 10a to be greatly increased, with consequent increased stability and lengthened electrode life. Because the pointed electrode tip protrudes from the shroud, the light y generated at the cathode footpoint or region is not shieldeLcFurthermore, the portion of such gas which drains throughtheannulus within shroud 19 is effective in producing stabilization of the discharge. I

The end result of the present apparatus and method is a highly stable, efficient, long-lasting light source. Furthermore, particles of additive may be introduced without causing instabilities-in the arc or spark.

The foregoing detailed description is tol be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

lclaim:

1. A radiation source, which comprises:

first and second electrodes having arcing portions disposed in spaced relationship from each other;

wall means to define a chamber incorporating said arcing portions, said wall means including a transparent window portion;

means to maintain an electric arc in said chamber between said arcing portions; and

means to introduce additive substance into said arc to alter the characteristics thereof, said last-mentioned means including means to entrain said additive substance in a carrier gas and to conduct the same to a region located in the vicinity of` said arc, said last-mentioned means further including means to drain carrier gas from said region whereby to minimize cooling and disruption of said arc by carrier gas.

2. The invention as claimed in claim 1, in which means are provided to pass arc-stabilizing gas continuously intol said chamber and to drain said arc-stabilizing gas continuously therefrom, said arc-stabilizing gas serving to stabilize said arc.

3. A radiation source, which comprises:

first and second electrodes having arcing portions disposed in spaced relationship from each other;

wall means to define a chamber incorporating said arcing portions, said wall means including a transparent window portion;

means to maintain an electric arc in said chamber between said arcing portions; means to pass arc-stabilizing gas continuously into said chamber and to drain said arc-stabilizing gas continuously therefrom, said gas means including means to pass said arc-stabilizing gas vortically about said arc to thereby stabilize and constrict the same; and

means to introduce additive substance into said arc to alter the characteristics thereof, said additive-introduction means including means to entrain said additive substance in a carrier gas and to conduct the same to a region 4with said arc.

toward `the cathode.

tion means further-including means to drain carrier gas from said region whereby to minimize cooling and disruption of said arc'bycarrier gas. v,

4. The invention as claimed in claim 1, in whichsaid means 'to introduce 'additive substance intoV said arc includes a passage'through one of said arcihg portions and communicating through a portwith said arcchamber, and further includes .tumof said additive substance carries the saine through said `port and into said chamber at said arc.

5. The invention las claimed in claim 4, in which'said means to introduce said additive substance is adapted` to introduce the same in the form of a particulate solid.

6. The invention as claimed in claim 4,- in which said conduit terminates in a nozzle `spaced from'said port in a direction away from said chamber, said nozzle andport being coaxial 7, A vortex-stabilized radiation source,rwhich comprises: wall means .toldene a chamber, atleast a portion of said wall means being formed of light-transmissive material,

l 'first-and second' electrodes disposed to effect an electrical discharge in said chamber, said electrodes having discharge portions disposed opposite each other and in .continuously introducing an ionizable gas at a high pressure into said chamber and in such manner that said gas flows vertically about an axis extending through said opening;

draining gas from said chamber simultan'eouslythrough said opening and through the shroud around said one electrode;

effecting an electrical discharge between said electrodes through said vortically flowing gas; and

transmitting radiation from said discharge through said light-transmissive wall portion.

l5. The invention as claimed in claiml4., in' which said lastnamed step includes connecting a DC 'source to said electrodes insuch manner that said one electrode is the cathode,

and employing said source to `maintain a steady-state `arc between said electrodes.

' 16. The invention as claimed in claim 1'4, in which said method includes maintaining the pressure in said opening only slightly lower than that in said chamber at the region thereof spaced relationship fromr each other, said discharge portion of said first electrode having an opening therein; means to continuously introduce an ionizable gas at a relatively high pressure into said chamber in such manner that said gas flows vortically in said chamber about an axis extending between said discharge portions; l means to effect an electrical discharge vbetween said discharge. p orftionsand along said axis; v means to drain gas continuously from said chamber through at least one path independent of said opening, and means to maintain the pressure in said opening only slightly lower than the pressure .in the partof said chamber which is adjacent said opening, whereby arninor proportion of said gas drains fromsaid chamber through said opening. 8.The invention as claimed in claim .7, in which lsaid means to effect an electrical discharge is a DC source so connected to said electrodes that saidsec'ond electrodeis the cathode. 9. The invention as claimed in claim 8, in which said gas-in troduction means comprises inlets disposed around said first electrode, whereby the general direction of vortical gas flow is l0. The inventionas claimed in claim v7, in which said means to effect an electrical discharge is a pulse or spark source.

ll. The invention as claimed inclaim 7, in which said means to drain gas from said chamber through at least one path inde'- perident of said opening includes a shroud provided around said second electrode. L i 12. The invention as claimedin claim 11., in whichsaidnected to said electrodesthat said second electrode is the cathode. l

14. A method of generating light and similar radiation through utilization of apparatus which comprises wall means l to define a chamber havinga light-transmissive wall porton, andalso comprises first and secondv electrodes provided in such chamber, one of said electrodes being shrouded and the other having a central opening thereinf-said method comprising: j f

claimed in claim 11, in which said' adjacent said opening, whereby only a relatively small amount of gas drains through said opening. 4

17. The invention as claimed in claim 14, in which said lastnamed step includes connecting a pulse-source to said electrodes, and employing said source to generate an electric I spark therebetween.

18. The invention as claimed in claim 15, in which said methodincludes introducing said gas into said chamber at a region around said other electrode.

19. A method of generating radiation, in the nature of light, through utilization of an electrical discharge chamber a wall portion of which is formed of light-transmissive material, and also through utilization of the opposed discharge portions ofiirst and second electrodes disposed in said chamber, which method comprises: continuously introducing an ionizable gas into said chamber and in such manner that at least part of said gas flows vortically about an axis 'extending between said discharge portions; l

e effecting an electrical discharge between said dischargeV portions and along said axis; n draining a small percentage of said gas from said chamber through the discharge portion of one lof said electrodes and at a location adjacent said axis; i draining a major percentage of said from said chamber through gas-outlet means independent of said one electrode and .spaced a substantial distance from said discharge portion of said one electrode; and

transmitting radiation from said discharge through said light-transmissive wall portion.

20. The invention as claimed in claim 19, in which said lastnamed step comprises draining gas from said chamber at a region adjacent said other of said electrodes.

2l. vThe invention as claimed in claim 19, in which said method comprises effecting said electrical discharge in the fomr of a DC arc, and causing said one electrode to be the anode. l

.22. The invention as claimed in claim 2l, in which said age of gas which is drained from said chamber independently of said discharge portion of said one electrode to drain through a shroud surrounding said other electrode.

'23. 'The invention as'claimed in claim 19, in which said method comprises effecting said electrical discharge in the form of a spark.

24. A radiation source, which comprises:` wall meansto define an arc chamber, -said wall means including a generally tubular light-transmissive envelope; an elongated cathode electrode extended into said chamber along the axis thereof; an elongated anode electrode vextended into the opposite end of said chamber along the axis thereof, the adjacent ends of said cathode and anode electrodes being spaced from each otheri ata high pressure means to drain gas from said chamber simultaneously from said annular gas-drainage passage and through said opening in said anode.

25. The invention as claimed in claim 24, in which said lastnamed means comprises means to drain a small percentage of the gas in said chamber through said opening in said anode, and a much larger percentage of the gas in said chamber through said annulus. 4

26. The invention as claimed in claim 24, in which means are provided to recirculate gas 'from said annulus, and from said anode opening, to said gas-inle't.r neans.

27. The invention as claimed inzvclaim 24, in which said inner end of said cathode is relatively small in diameter and protrudes a substantial distance from said shroud.

UNITED STATES PATENT OFFICE 56g CERTIFICATE 0F CORRECTION Dated December 29, 1970 Patent No. 3, 551, 737

Inventor(s) Ronald E. Sheets It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

cancel "said carrier"; line 12,

r- Colurnn 5, line 11,

n commumcatmg WItk cancel "gas from said region includes a drei Signed and sealed this 10th day of August 1971.

(SEAL) Attest:

EDWARD M.FLETGHER,JR. WILLIAM E. SGHUYLER, JR. Attesting Officer Commissioner of Patents 

